Low iron availability in continuous in vitro colonic fermentations induces strong dysbiosis of the child gut microbial consortium and a decrease in main metabolites

Iron (Fe) deficiency affects an estimated 2 billion people worldwide, and Fe supplements are a common corrective strategy. The impact of Fe deficiency and Fe supplementation on the complex microbial community of the child gut was studied using in vitro colonic fermentation models inoculated with immobilized fecal microbiota. Chyme media (all Fe chelated by 2,2′-dipyridyl to 26.5 mg Fe L−1) mimicking Fe deficiency and supplementation were continuously fermented. Fermentation effluent samples were analyzed daily on the microbial composition and metabolites by quantitative PCR, 16S rRNA gene 454-pyrosequencing, and HPLC. Low Fe conditions (1.56 mg Fe L−1) significantly decreased acetate concentrations, and subsequent Fe supplementation (26.5 mg Fe L−1) restored acetate production. High Fe following normal Fe conditions had no impact on the gut microbiota composition and metabolic activity. During very low Fe conditions (0.9 mg Fe L−1 or Fe chelated by 2,2′-dipyridyl), a decrease in Roseburia spp./Eubacterium rectale, Clostridium Cluster IV members and Bacteroides spp. was observed, while Lactobacillus spp. and Enterobacteriaceae increased consistent with a decrease in butyrate (−84%) and propionate (−55%). The strong dysbiosis of the gut microbiota together with decrease in main gut microbiota metabolites observed with very low iron conditions could weaken the barrier effect of the microbiota and negatively impact gut healt

Clostridium difficile colonization and antibiotics response in PolyFermS continuous model mimicking elderly intestinal fermentation

Abstract Background Clostridium difficile (CD), a spore-forming and toxin-producing bacterium, is the main cause for antibiotic-associated diarrhea in the elderly. Here we investigated CD colonization in novel in vitro fermentation models inoculated with immobilized elderly fecal microbiota and the effects of antibiotic treatments. Methods Two continuous intestinal PolyFermS models inoculated with different immobilized elder microbiota were used to investigate selected factors of colonization of CD in proximal (PC, model 1) and transverse-distal (TDC, model 1 and 2) colon conditions. Colonization of two CD strains of different PCR ribotypes, inoculated as vegetative cells (ribotype 001, model 1) or spores (ribotypes 001 and 012, model 2), was tested. Treatments with two antibiotics, ceftriaxone (daily 150 mg L−1) known to induce CD infection in vivo or metronidazole (twice daily 333 mg L−1) commonly used to treat CD, were investigated in TDC conditions (model 2) for their effects on gut microbiota composition (qPCR, 16S pyrosequencing) and activity (HPLC), CD spore germination and colonization, and cytotoxin titer (Vero cell assay). Results CD remained undetected after inoculating vegetative cells in PC reactors of model 1, but was shown to colonize TDC reactors of both models, reaching copy numbers of up to log10 8 mL−1 effluent with stable production of toxin correlating with CD cell numbers. Ceftriaxone treatment in TDC reactors showed only small effects on microbiota composition and activity and did not promote CD colonization compared to antibiotic-free control reactor. In contrast, treatment with metronidazole after colonization of CD induced large modifications in the microbiota and decreased CD numbers below the detection limit of the specific qPCR. However, a fast CD recurrence was measured only 2 days after cessation of metronidazole treatment. Conclusions Using our in vitro fermentation models, we demonstrated that stable CD colonization in TDC reactors can be induced by inoculating CD vegetative cells or spores without the application of ceftriaxone. Treatment with metronidazole temporarily reduced the counts of CD, in agreement with CD infection recurrence in vivo. Our data demonstrate that CD colonized an undisturbed microbiota in vitro, in contrast to in vivo observations, thus suggesting an important contribution of host-related factors in the protection against CD infection

Neuronal basis of emotion processing and regulation in conduct disorder

Emotion regulation, a key component of healthy development, has been shown to be deficient in several psychiatric conditions, including conduct disorder. Conduct disorder is a neuropsychiatric disorder of childhood and adolescence characterized by severe aggressive behavior and violation of societal norms. It is highly prevalent and results in substantial economic costs and negative social consequences. Neuroimaging evidence has revealed brain activity alterations in several regions, including prefrontal, temporal, and limbic cortex (amygdala, insula, and cingulate gyrus). While the neuronal basis of emotion processing in conduct disorder has been intensely investigated, the brain correlates of implicit and explicit emotion regulation remain unclear. The main aim of this dissertation was to extend current knowledge by investigating the neuronal mechanisms of emotion regulation in children and adolescents with conduct disorder. First, we conducted a meta-analysis in order to identify the neuronal correlates of emotion processing in adolescents with aggressive behavior. We then developed an affective Stroop task designed to investigate the interplay between emotion and cognition in a paediatric population, and validated it in healthy young adults. We then employed the task to study the neuronal characteristics of implicit emotion-cognition interaction in children and adolescents with conduct disorder. Finally, we investigated explicit emotion regulation by cognitive reappraisal (i.e., reinterpretation of the meaning of an emotional stimulus) in conduct disorder. We here present findings on altered brain function during tasks assessing implicit and explicit emotion regulation in adolescents with conduct disorder that are in agreement with behaviorally observed deficits. Our meta-analysis on emotion processing in conduct disorder summarized previous literature indicating prefrontal and limbic brain structure and function alterations. The results from our study employing the affective Stroop task in healthy adults validated the usefulness of our task design and replicated previous findings suggesting that emotion significantly impacts cognition on a behavioral and neuronal level. Using the affective Stroop and cognitive reappraisal tasks in adolescents with conduct disorder revealed neuronal alterations within prefrontal and limbic regions, brain areas implicated in both emotion and cognition. Overall, the results of this dissertation provide novel evidence on the neuronal basis of emotion regulation deficits in conduct disorder. Future studies shall further investigate emotion regulation in specific subgroups of conduct disorder, for example those with psychopathic traits or high levels of anxiety with the ultimate goal of influencing the child’s immediate environment and society as a whole

Ella and Marion Hepworth Dixon: ‘What’s in a Name?’

‘The name, of course, [...] the name counts for something. Your late father’s name carries weight with a certain section of the public’, declares a fictional editor in Ella Hepworth Dixon’s seminal New Woman novel, The Story of a Modern Woman (1894).[i] One cannot help wondering if the name ‘Hepworth Dixon’ resonated in the same way for Henry Harland and John Lane, the editors of The Yellow Book, which began that same year. The name had definitely acquired a certain notoriety earlier in the century when William Hepworth Dixon (1821-1879) had been editor of The Athenæum from 1853 to 1869, but by 1894 two of his daughters, Marion (1856-1936) and her younger sister, Ella (1857-1932), had begun to make names for themselves in the literary world.   [i] Ella Hepworth Dixon, The Story of a Modern Woman (Broadview, 2004), p. 108. Italics in original. Initially serialised in twelve weekly instalments in the Lady’s Pictorial between January and March 1894, then published in book form later that year by Heinemann in London and Cassell in New York, the novel has since been republished several times, first in 1990 in the Merlin Radical Fiction series. All subsequent page references will refer to the Broadview edition

A microarray configuration to quantify expression levels and relative abundance of splice variants

Over the past decade, alternative RNA splicing has raised a great interest appearing to be of high importance in the generation of expression diversity. This regulatory process plays a critical role in the normal development and its impact on the initiation and development of human disorders as well as on the pharmacological properties of drugs is increasingly being recognized. Only few studies describe specific alternative splicing expression profiling. Microarray strategies have been conceived to address alternative splicing events but with very few experimental data related to their abilities to provide true quantification values. We have developed a specific microarray configuration relying on a few, well optimized probes per splice event. Basically, five probes of 24mer are used to fully characterize a splice event. These probes are of two types, exon probes and junction probes, and are either specific to a splice event or not. The performances of such a ‘splice array’ were validated on synthetic model systems and on complex biological materials. The results indicate that DNA chips based on this design combining exon and junction derived probes enable the detection and, absolute and relative quantification of splice variants. In addition, this strategy is compatible with all the microarrays that use oligonucleotide probes

Sex Ex Libris: Abstinence Messages in High School Health Textbooks Cultivate Sex Negativity Among Teens

The vast majority of high schools require some form of sex education. Despite numerous concerns about the efficacy of abstinence-only education programs and their failure to demonstrate a reduction in the onset of teenage sexual activity, such curricula remains widespread in U.S. public schools. One resource in formal sex education is health textbooks. Six widely used high school health textbooks were investigated. Through qualitative content analysis of the written material, a shared emphasis on abstinence was identified, specifically in relation to premarital relationships, decision-making, and risk prevention. Textbooks emphasize that marriage is the only appropriate place for people to have sex, aim to instruct teens on how to make responsible decisions and how to refuse engaging in deviant behavior, and stress that sex is a high-risk activity that teens should avoid in favor of abstinence. Using the data from these high school health textbooks, I develop a theory of patronizing exclusivism to explain the implicit and explicit messages about abstinence and identify six primary features: perpetuation of the stereotypical ideal family, denial of demographic realities, assumption that teens are impulsive, conflation of sex with morality, encouragement of stigma of the sexually active, and promotion of sex negativity. Promotion of sex negativity is the root strategy and facilitates the implicit and explicit messages about abstinence in high school health textbooks. The theory of patronizing exclusivism has implications relevant to dialogue about how sex education should be taught and what should be included

Do magnification loupes affect the precision of cavity preparations made by undergraduates? A randomized crossover study.

BACKGROUND Evidence on the effect of magnification devices on procedure quality in restorative dentistry is scant. This study therefore aimed to assess, under simulated clinical conditions, if magnification loupes affect the quality of preparations carried out by undergraduate dental students. METHODS 59 undergraduate dental students underwent two visual acuity tests, based on which they were divided into a "low visual acuity group" (visus < 1) and a "good visual acuity group" (visus ≥ 1). In a randomized crossover experiment, participants performed a two-dimensional S and a three-dimensional O figure preparation with a dental handpiece on standardized acrylic blocs designed for preclinical restorative training. Each participant carried out the preparation tasks twice, once with magnification loupes (2.5×) and once without. Two blinded investigators independently evaluated parameters of preparation precision. Data were analyzed using Spearman rank correlation coefficients, intra-class correlation coefficients, and Wilcoxon rank-sum tests (α = 0.05). RESULTS Participants from the "low visual acuity group" did not show a statistically significant improvement in accuracy when they used magnification loupes for the S figure preparation (p ≥ 0.0625). Participants from the "high visual acuity group" obtained a higher level of accuracy (p ≤ 0.0012) when they used magnification loupes for the S figure preparation. The use of magnification loupes had no statistically significant effect on the accuracy parameters of the O figure cavity preparations (p ≥ 0.1865). Participants with high visual acuity achieved only a marginally better accuracy than participants with a visus < 1. CONCLUSIONS This study suggests that loupes with 2.5× magnification increase the accuracy of two-dimensional preparations while they have no significant effect, favorable or otherwise, on the accuracy of complex, three-dimensional cavity preparations of untrained dental students

Microstructural white matter alterations in the corpus callosum of girls with conduct disorder

Objective Diffusion tensor imaging (DTI) studies in adolescent conduct disorder (CD) have demonstrated white matter alterations of tracts connecting functionally distinct fronto-limbic regions, but only in boys or mixed-gender samples. So far, no study has investigated white matter integrity in girls with CD on a whole-brain level. Therefore, our aim was to investigate white matter alterations in adolescent girls with CD. Method We collected high-resolution DTI data from 24 girls with CD and 20 typically developing control girls using a 3T magnetic resonance imaging system. Fractional anisotropy (FA) and mean diffusivity (MD) were analyzed for whole-brain as well as a priori−defined regions of interest, while controlling for age and intelligence, using a voxel-based analysis and an age-appropriate customized template. Results Whole-brain findings revealed white matter alterations (i.e., increased FA) in girls with CD bilaterally within the body of the corpus callosum, expanding toward the right cingulum and left corona radiata. The FA and MD results in a priori−defined regions of interest were more widespread and included changes in the cingulum, corona radiata, fornix, and uncinate fasciculus. These results were not driven by age, intelligence, or attention-deficit/hyperactivity disorder comorbidity. Conclusion This report provides the first evidence of white matter alterations in female adolescents with CD as indicated through white matter reductions in callosal tracts. This finding enhances current knowledge about the neuropathological basis of female CD. An increased understanding of gender-specific neuronal characteristics in CD may influence diagnosis, early detection, and successful intervention strategies

An in vitro chicken gut model demonstrates transfer of a multidrug resistance plasmid from Salmonella to commensal Escherichia coli

The chicken gastrointestinal tract is richly populated by commensal bacteria that fulfill various beneficial roles for the host, including helping to resist colonization by pathogens. It can also facilitate the conjugative transfer of multidrug resistance (MDR) plasmids between commensal and pathogenic bacteria which is a significant public and animal health concern as it may affect our ability to treat bacterial infections. We used an in vitro chemostat system to approximate the chicken cecal microbiota, simulate colonization by an MDR Salmonella pathogen, and examine the dynamics of transfer of its MDR plasmid harboring several genes, including the extended-spectrum beta-lactamase blaCTX-M1 We also evaluated the impact of cefotaxime administration on plasmid transfer and microbial diversity. Bacterial community profiles obtained by culture-independent methods showed that Salmonella inoculation resulted in no significant changes to bacterial community alpha diversity and beta diversity, whereas administration of cefotaxime caused significant alterations to both measures of diversity, which largely recovered. MDR plasmid transfer from Salmonella to commensal Escherichia coli was demonstrated by PCR and whole-genome sequencing of isolates purified from agar plates containing cefotaxime. Transfer occurred to seven E. coli sequence types at high rates, even in the absence of cefotaxime, with resistant strains isolated within 3 days. Our chemostat system provides a good representation of bacterial interactions, including antibiotic resistance transfer in vivo It can be used as an ethical and relatively inexpensive approach to model dissemination of antibiotic resistance within the gut of any animal or human and refine interventions that mitigate its spread before employing in vivo studies.IMPORTANCE The spread of antimicrobial resistance presents a grave threat to public health and animal health and is affecting our ability to respond to bacterial infections. Transfer of antimicrobial resistance via plasmid exchange is of particular concern as it enables unrelated bacteria to acquire resistance. The gastrointestinal tract is replete with bacteria and provides an environment for plasmid transfer between commensals and pathogens. Here we use the chicken gut microbiota as an exemplar to model the effects of bacterial infection, antibiotic administration, and plasmid transfer. We show that transfer of a multidrug-resistant plasmid from the zoonotic pathogen Salmonella to commensal Escherichia coli occurs at a high rate, even in the absence of antibiotic administration. Our work demonstrates that the in vitro gut model provides a powerful screening tool that can be used to assess and refine interventions that mitigate the spread of antibiotic resistance in the gut before undertaking animal studies